compare two tables and select matching column table

Question

I have two tables with exactly the same columns

table ' a'
sno       id    name          mobile
1        1001   shashi     8985500134
2        1002    raju        7896543211

table 'b'
sno   id       name     mobile
1    1001    shashi      8985500134
2    10005   aravind    9900123456

compare two tables and select mobile column 
select query in sql that will display all rows in Table A where the mobile column is the same as Table B but having matching ID's columns..........


i want output like this.....................
sno     id        name          mobile
1      1001     shashi        8985500134


compare table a ,table b and display matching table a cooloum